Vehicular electrical architecture of both wireless power and communication peripherals using MRC

ABSTRACT

A system for providing power signals to peripheral devices on a vehicle using magnetic resonance coupling. The system includes a transmitter circuit having a variable current source, a base coil and a variable capacitor, where the current source and the capacitor are tuned to provide a predetermined AC current to the base coil so as to generate an oscillating magnetic field at a predetermined frequency. The system also includes a receiver circuit for each peripheral device, where each receiver circuit includes a receiver coil and a rechargeable power source. When the base coil is tuned to the receiver coil the power source can be recharged through magnetic resonance coupling to power the device. The transmitter circuit can be on the vehicle or can be separate from the vehicle, such as in a charging pad.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the priority date of U.S.Provisional Patent Application Ser. No. 61/945,720, titled, VehicularElectrical Architecture of Both Wireless Power and CommunicationPeripherals Using MRC, filed Feb. 27, 2014.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates generally to a system and method for providingpower signals to peripheral devices using magnetic resonance coupling(MRC) and, more particularly, to a system and method for providing powersignals to a plurality of peripheral devices on a vehicle using MRC,where a single transmitter coil provides power coupling to a secondarycoil on each of the peripheral devices, and where the transmitter coilis integrated on the vehicle or is exterior to the vehicle.

Discussion of the Related Art

Modern vehicles employ many sensors, actuators, controllers,sub-systems, buses, etc. that require electrical wiring to operate thedevices. As the number of vehicle systems increases, so does the wiringnecessary to support those systems. However, there are a number ofdisadvantages with providing wires in a vehicle, especially many wires.For example, the electrical conductor of the wires, such as copper, hassignificant weight. As the weight of a vehicle increases, fuelefficiency decreases. Further, wiring in a vehicle is susceptible todamage, which increases the warranty cost of the vehicle. Also,requiring wiring throughout the vehicle reduces the flexibility indesign and manufacturing of the vehicle. Further, at least some of thewiring in a vehicle often requires periodic maintenance. Also, wiringadds significant expense and cost. Further, during manufacture of thevehicle, assembly of cable harnesses often causes problems as a resultof breaking or bending of connector pins. Therefore, it would bedesirable to eliminate or reduce the wiring in a vehicle.

It is known in the art to employ wireless technology in a vehicle forcommunications purposes at least in limited circumstances. However, thetransmission of wireless signals also suffers from a number ofdisadvantages including interference with signals from other vehicles,potential interference with signals from consumer devices brought intothe vehicle, unnecessary radiation inside the passenger compartment ofthe vehicle, and fading issues, which result in loss of signal,requiring larger transmitted power and large power consumption.

SUMMARY OF THE INVENTION

The following disclosure describes a system and method for providingpower signals to peripheral devices on a vehicle using magneticresonance coupling. The system includes a transmitter circuit having avariable current source, a base coil and a variable capacitor, where thecurrent source and the capacitor are tuned to provide a predetermined ACcurrent to the base coil so as to generate an oscillating magnetic fieldat a predetermined frequency. The system also includes a receivercircuit for each peripheral device, where each receiver circuit includesa receiver coil and a chargeable power source. When the base coil istuned to the receiver coil the power source can be recharged throughmagnetic resonance coupling to power the device. The transmitter circuitcan be on the vehicle or can be separate from the vehicle, such as in acharging pad.

Additional features of the present invention will become apparent fromthe following description and appended claims, taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a vehicle including a transmitter coilencircling a plurality of peripheral devices each including secondarycoils;

FIG. 2 is a schematic diagram of a magnetic resonance coupling circuitincluding a transmitter side and a receiver side;

FIG. 3 is an isometric view of a vehicle parked on a charging pad; and

FIG. 4 is a schematic diagram of an analog sensor circuit.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following discussion of the embodiments of the invention directed toa magnetic resonance coupling system for providing power signals toperipheral devices on a vehicle is merely exemplary in nature, and is inno way intended to limit the invention or its applications or uses. Forexample, as discussed, the magnetic resonance coupling system hasparticular application for peripheral devices on a vehicle. However, aswill be appreciated by those skilled in the art, the magnetic resonancecoupling system may have other applications on other mobile platforms,such as on trains, machines, tractors, boats, recreation vehicles, etc.

The present invention proposes a system and method for providingwireless power and data communications through magnetic resonancecoupling (MRC) for various peripheral devices, such as switches,actuators, sensors, etc., on a vehicle. As is well understood by thoseskilled in the art, MRC employs a quasi-static magnetic field betweentwo or more coils, where the coils are tuned to resonate at the samefrequency. An alternating current is provided on one of the coils, whichgenerates an oscillating magnetic field. The oscillating magnetic fieldis received by the other coil that induces an oscillating current inthat coil, which can be used to charge a power source, such as acapacitor or a rechargeable battery, and can be used to provide highrate data transfer, as will be discussed in detail below.

In one embodiment, the MRC system includes a relatively large base coil,sometimes referred to herein as a transmitter coil, and several smallersecondary or receiver coils each provided as part of a peripheraldevice. FIG. 1 is a top view of a vehicle 10 including an electroniccontrol unit (ECU) 12 for a particular sub-system of the vehicle 10,such as an engine controller. A large base coil 14 is embedded in thevehicle 10 at the particular location of the sub-system, where the coil14 encloses all of the peripheral devices that are part of thatsub-system. Particularly, a number of peripheral devices 16, such asswitches, actuators, sensors, etc., are provided within the base coil 14and each includes its own secondary coil 18. As will be discussed, thebase coil 14 is controlled to resonate at a particular frequency andproduce an oscillating magnetic field that is received by the coils 18that can then be used to charge a power source in the device 16 throughmagnetic resonance coupling. Also, the magnetic resonance coupling canbe used for data transfer between the ECU 12 and the devices 16. Inorder to provide the most efficient transfer of energy from the basecoil 14 to the secondary coils 18, it is desirable, but not necessary,that all of the devices 16 be positioned within the coil 14, andpreferably on the same plane as the coil 14. In one embodiment, theperipheral device is an LED tail light 20 on the vehicle 10 that ispowered by the base coil 14 and/or receives communications signals fromthe base coil 14, for example, to turn on the light 20, consistent withthe discussion herein.

FIG. 2 is a schematic diagram of an MRC circuit 30 separated from thevehicle 10. The circuit 30 includes a transmitter side 32 and a sensoror receiver side 34, where the receiver side 34 includes one of theperipheral devices 16 that may receive power signals from thetransmitter side 32. In this non-limiting embodiment, the receiver side34 includes a sensor 38. The transmitter side 32 includes a base coil36, representing the base coil 14, and a controller or ECU 40,representing the ECU 12. The ECU 40 includes a variable current source42 that provides an alternating current that is tuned by a variabletuning capacitor 44 in conjunction with a variable load 46, which causesthe coil 36 to generate an oscillating magnetic field at a particularfrequency. The source 42 and the variable capacitor 44 can beselectively controlled by the ECU 40 to provide different frequencies sothat the base coil 36 can be tuned to multiple resonant frequencies ifdesired. In one non-limiting embodiment, the ECU 40 can employ pulsewidth modulation (PWM) to vary the frequency of the current provided bythe source 42, which changes the resonate frequency of the coil 36. Thetransmitter side 32 also includes a mini-loop 48 that provides impedancematching between the load 46 and the source 42. It is noted that themini-loop 48 is not required for some embodiments. An impedance meter 50allows the ECU 40 to estimate measurement signals from an analog sensorcircuit or decode digital signals from a digital sensor circuit, as willbe discussed in more detail below.

The receiver side 34 includes a receiver coil 60 that generates acurrent in response to the oscillating magnetic field received from thebase coil 36. The receiver side 34 also includes a mini-loop 68providing impedance matching to the coil 60. It is noted that themini-loop 68 is not required for some embodiments. An optional fixed LCnetwork 66 can be provided in the circuit to help provide impedancematching between the mini-loop 68 and the receiver coil 60. As themagnetic field oscillates, the receiver coil 60 generates an AC signal,which is tuned to a particular resonant frequency by a tuning capacitor62, so that the resonant frequency of the coil 60 provides strongmagnetic coupling with the base coil 36 when the oscillating magneticfield is at the tuned frequency of the coil 60. When the oscillatingmagnetic field is tuned to one or more of the receiver coils 60 so thatan alternating current signal is generated therein, that current can beused to charge a rechargeable power source 64, such as a rechargeablebattery or super-capacitor, in the receiver side 34, which includes arectifier to convert the AC signal to a DC signal. The power stored inthe power source 64 can then be used to provide power for the sensor 38.Each of the peripheral devices associated with a particular transmittercircuit can be tuned to the same frequency and receive power signals atthe same time. Alternately, such as for data transfer applications, oneor more of the receiver coils 60 in the peripheral devices 16 can betuned to a different frequency, and each of those frequencies can beprovided by the transmitter circuit 32 by controlling the current source42 and the capacitor 44. It is further noted that multiple base coilscan be associated with a single controller to allow for communicationswith several peripherals in parallel.

Because of the size, weight and other requirements of the base coil 36,it may be desirable to remove the base coil 36 from the vehicle 10, ifpossible. In an alternate embodiment, the base coil or coils for thevarious vehicle sub-systems is removed from the vehicle 10 and a singlecoil is employed in a charging station to charge all of the peripheraldevices 16 on the vehicle 10, and possibly a vehicle battery. It isknown in the art to provide a charging station for an electric vehicle,where the charging station includes a charging pad having a coil thatcharges the vehicle battery through magnetic resonance coupling. Thepresent invention proposes using the same charging pad for charging thevehicle battery to also charge the various peripheral devices 16 on thevehicle 10.

This embodiment is illustrated in FIG. 3 showing a vehicle 70 parked ona charging pad 72, such as may be mounted in the floor of a garage. Thecharging pad 72 includes a coil or power track 74 that is coupled to anAC power source (not shown), such as an electrical outlet in the garage.The power track 74 generates an oscillating magnetic field that chargesa vehicle battery 76 on the vehicle 70 in the known manner. That sameoscillating magnetic field can be used to provide power to one or moreperipheral devices 78 on the vehicle 70. In this way, the large basecoil is not required to be on the vehicle 70.

The discussion above talks about using magnetic resonance coupling towirelessly provide power for peripheral devices on a vehicle. If thetransmitter side 32 is only providing power signals to a plurality ofperipheral devices each including a separate receiver coil, then each ofthe receiver coils can be tuned to a single frequency and all be poweredsimultaneously when the transmitter side 32 is providing the oscillatingmagnetic field. The present invention also proposes using the samemagnetic resonance coupling, such as between the base coil 36 and thereceiver coil 60, to provide a transfer of data from the peripheraldevice 16 if the device is a sensor, such as a temperature sensor,pressure sensor, stress sensor, force sensor, etc., to the ECU 40. Thisembodiment assumes that the base coil 36 is on the vehicle 10, and isnot part of the charging pad 72. If the magnetic resonance coupling isbeing used for data transfer, then the receiver circuits for the severalsensors can be tuned to different frequencies so as to preventinterference between the data signals being sent. Tuning the base coil36 for the several resonant frequencies can be provided by scanningthrough the frequencies, for example, using time division multiplexing,by selectively controlling the tuning provided by the capacitor 44 andthe power source 42. Circuitry can also be provided that allows thetransmitter side 32 to send control signals to the receiver side 34 alsothrough magnetic resonance coupling.

As will be discussed in detail below, the present invention proposes twotechniques for obtaining sensor data from the sensor at the ECU 40through magnetic resonance coupling. For the first technique, discussedwith reference to FIG. 2, where the receiver side 34 is an analog sensorcircuit, the sensor 38 itself is a resistive device whose compleximpedance changes in response to the environmental condition beingsensed, and that impedance is read directly into the secondary coilcircuitry. The sensor 38 provides a certain resistance depending on thecondition that is being sensed, such as pressure, temperature, strain,etc. The sensor 38 is electrically coupled to the mini-loop 68 thatprovides impedance matching between the sensor 38 and the receiver coil60. When the resistance of the sensor 38 changes a variation occurs inthe magnetic coupling between the coils 38 and 60, which causes a changein the current flow through the coil 36, which in turn changes thevoltage across the load 46 that is detected by the ECU 40 to provide anindication of the sensor measurement.

A calibration resistor 52 can also be provided as part of the sensor 38in an optional embodiment that can be switched into the receiver circuitby a switch 54 to provide a fixed impedance for calibration purposes.Particularly, since the change in resistance of the sensor 38 inresponse to the measured environmental condition may drift over time, itmay be desirable to provide a known impedance into the coil circuit onthe receiver side 34 that can be detected by the ECU 40 for dynamiccalibration purposes.

The second data transfer technique translates the sensor reading ormeasurement to a digital value that is encoded or translated into asequence of complex loads that are switched into the receiver coil. FIG.4 is a schematic diagram of a digital sensor circuit 80 similar to thereceiver side 34 of the circuit 30 to illustrate this embodiment. Thecircuit 80 includes a sensor coil 82 having a variable tuning capacitor4. The circuit 80 also includes a mini-loop 86 that provides impedancematching, as discussed above. It is noted that the mini-loop 86 is notrequired for some embodiments. The digital sensor circuit 80 furtherincludes a sensor 88 that provides an analog signal that is thenconverted to a digital signal in a microcontroller 90. The circuit 80also includes a rectifier and energy storage device 92 that is chargedto provide power for the circuit 80. As above, an optional fixed LCnetwork 94 can be provided for impedance matching purposes.

The microcontroller 90 includes, for example, a table that stores amatrix of complex loads, where each load identifies a particularmeasurement of the sensor 88. Depending on the value of the digitalsignal received by the microcontroller 90, the microcontroller 90selects the sequence of appropriate complex loads from the table andencodes it as a sequence of digital bits that control switches in thecircuitry of the coil 82 through a variable complex impedance load,which provides a digital QAM type of modulation of the current flowwithin the coil 82. This modulated impedance load affects the strongmagnetic resonance coupling between the coils 36 and 82 that alters thecurrent flow through the coil 36, which changes the voltage across theresistive load 46 in the base coil circuit, where that voltage changeacross the resistive load 46 can be detected by the ECU 40, thusproviding an indication of the sensor measurement to the ECU 40. Byselectively tuning the base coil 36 to the resonant frequency of aparticular receiver coil, data from the sensor associated with that coilcan be obtained.

Depending on the value of the sensor signal received and digitallyconverted by the microcontroller 90, the microcontroller 90 controls oneor more switches 96 in a fixed complex load ladder 98 to selectivelyswitch loads 100 into the circuit 80. As discussed above, based on themeasured sensor value, the microcontroller 90 chooses a load 100, or acombination of the loads 100, as the complex load to be coupled to thetransmitter circuit. If the complex load is represented by a one bytevalue, at most 256 different complex load bits are needed. Fewer loadscan be employed by using a combination of switches or sequentiallyencoding fewer bits, for example, two bits at a time, requiring onlyfour different complex loads, and four time slots to complete thetransmission. The complex loads 100 are chosen so that the minimumdistance between the constellation points in the digital signal ismaximized to increase the signal-to-noise ratio performance. Also, asabove with the analog sensor, a known sequence of the loads 100 can beswitched into the circuit as a reference to compensate for variations,drift, etc., in the magnetic field coupling for dynamic calibrationpurposes.

As discussed above, the same magnetic resonance coupling betweentransmitter circuit and receiver circuit can be used to provide bothpower for the receiver circuit and data transfer from the receiver tothe transmitter circuit. The transmitter circuit switches to a resonantfrequency that matches a particular sensor circuit to provide power forthe sensor circuit and then reads its measurement signal. Thetransmitter circuit then switches its resonant frequency to the nextsensor and so on. The time that the transmitter circuit dwells on aparticular sensor circuit is the time required to power the sensor, makethe sensor reading and allow for it to communicate back to thetransmitter circuit. For the analog sensor circuit this time frame isalmost instantaneous, where some time is needed to allow for thefrequency to stabilize. For the digital sensor circuit, the time shouldbe such that enough energy is accumulated in the rectifier and energystorage device to allow for the microcontroller to wake up and performthe measurement and transmit the information back to the transmittercircuit. This time may take several milliseconds depending on thedistance, sensor requirements, etc.

As discussed above, both the analog sensor embodiment and the digitalsensor embodiment provides sensor signals through magnetic resonancecoupling that are received by the transmitter circuit. In an alternateembodiment, both the analog sensor circuit and the digital sensorcircuit can include a controller and impedance meter so as to allow thetransmitter circuit to send signals, such as commands, to the sensorcircuit.

The foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. One skilled in the art willreadily recognize from such discussion and from the accompanyingdrawings and claims that various changes, modifications and variationscan be made therein without departing from the spirit and scope of theinvention as defined in the following claims.

What is claimed is:
 1. A magnetic resonance coupling (MRC) circuitcomprising: at least one transmitter circuit including a base coil and avariable current source, said variable current source selectivelyproviding a predetermined current to the base coil so as to generate anoscillating magnetic field at a predetermined frequency; and a pluralityof peripheral circuits for a plurality of peripheral devices, eachperipheral circuit including a receiver coil and a rechargeable powersource, each receiver coil being tuned to a resonant frequency, saidtransmitter circuit selectively providing the frequency of theoscillating magnetic field to be tuned to one or more of the receivercoils so as to charge the power source in the particular peripheralcircuit through magnetic resonance coupling, where each peripheralcircuit further includes a variable complex impedance load, wherein achange in the complex impedance load in a peripheral circuit causes achange in the magnetic coupling between the base coil and the receivercoil that causes a change in the voltage across a control load in thetransmitter circuit that allows data transfer between the transmittercircuit and the peripheral circuit.
 2. The MRC circuit according toclaim 1 wherein the transmitter circuit and the plurality of peripheraldevices are on a vehicle.
 3. The MRC circuit according to claim 2wherein the base coil encircles all of the peripheral devices.
 4. TheMRC circuit according to claim 2 wherein the peripheral devices are onthe same plane as the base coil.
 5. The MRC circuit according to claim 1wherein the plurality of peripheral devices are on a vehicle and thetransmitter circuit is external to the vehicle.
 6. The MRC circuitaccording to claim 5 wherein the transmitter circuit is part of acharging pad for charging a vehicle battery.
 7. The MRC circuitaccording to claim 1 wherein the at least one transmitter circuit is aplurality of transmitter circuits each including a base coil and avariable current source, where all of the transmitter circuits arecontrolled by a common microcontroller.
 8. The MRC circuit according toclaim 1 wherein the base coil and each of the receiver coils include atuning capacitor.
 9. The MRC circuit according to claim 1 wherein theperipheral devices are selected from the group consisting of switches,actuators, sensors and lights.
 10. A magnetic resonance coupling (MRC)circuit for providing power signals to a plurality of peripheral deviceson a vehicle, said MRC circuit comprising: at least one transmittercircuit on the vehicle and including a controller, a base coil, avariable current source and a tuning capacitor, said variable currentsource selectively providing a predetermined alternating current to thebase coil in combination with the tuning capacitor so as to generate anoscillating magnetic field at a predetermined frequency; and a pluralityof receiver circuits where a separate receiver circuit is provided foreach of the plurality of peripheral devices, each receiver circuitincluding a receiver coil, a tuning capacitor and a rechargeable powersource, where each of the receiver circuits is tuned to a differentresonant frequency, said controller in the transmitter circuitselectively providing the frequency of the oscillating magnetic field tobe tuned to each one of the receiver coils at a different time, so as tocharge the power source in the particular receiver circuit throughmagnetic resonance coupling.
 11. The MRC circuit according to claim 10wherein the base coil encircles all of the peripheral devices.
 12. TheMRC circuit according to claim 10 wherein the at least one transmittercircuit is a plurality of several transmitter circuits each including abase coil, a variable current source and a tuning capacitor, where allof the transmitter circuits are controlled by a common microcontroller.13. The MRC circuit according to claim 10 wherein each receiver circuitfurther includes a variable complex impedance load, wherein a change inthe complex impedance load in a receiver circuit causes a change in themagnetic coupling between the base coil and the receiver coil thatcauses a change in the voltage across a control load in the transmittercircuit that allows data transfer between the transmitter circuit andthe receiver circuit.
 14. The MRC circuit according to claim 10 whereinthe peripheral devices are selected from the group consisting ofswitches, actuators, sensors and lights.
 15. A magnetic resonancecoupling (MRC) circuit for providing power signals to a plurality ofperipheral devices on a vehicle, said MRC circuit comprising: at leastone transmitter circuit external to the vehicle and including acontroller, a base coil, a variable current source and a tuningcapacitor, said variable current source selectively providing apredetermined alternating current to the base coil in combination withthe tuning capacitor so as to generate an oscillating magnetic field ata predetermined frequency; and a plurality of receiver circuits where aseparate receiver circuit is provided for each of the plurality ofperipheral devices, each receiver circuit including a receiver coil, atuning capacitor and a rechargeable power source, where each of thereceiver circuits is tuned to a different resonant frequency, saidcontroller in the transmitter circuit selectively providing thefrequency of the oscillating magnetic field to be tuned to each one ofthe receiver coils at a different time, so as to charge the power sourcein the particular receiver circuit through magnetic resonance coupling.16. The MRC circuit according to claim 15 wherein the transmittercircuit is part of a charging pad for charging a vehicle battery. 17.The MRC circuit according to claim 15 wherein the at least onetransmitter circuit is a plurality of several transmitter circuits eachincluding a base coil, a variable current source and a tuning capacitor,where all of the transmitter circuits are controlled by a commonmicrocontroller.
 18. The MRC circuit according to claim 15 wherein eachreceiver circuit further includes a variable complex impedance load,wherein a change in the complex impedance load in a receiver circuitcauses a change in the magnetic coupling between the base coil and thereceiver coil that causes a change in the voltage across a control loadin the transmitter circuit that allows data transfer between thetransmitter circuit and the receiver circuit.
 19. The circuit accordingto claim 15 wherein the peripheral devices are selected from the groupconsisting of switches, actuators, sensors and lights.